Hi R used with C-code experts,
I had a look at the archives and did not find anything on this, so
hopefully I am not doubling up.
I have previously used the following approach where I needed some very
small/large numbers (using Brobdingnag):
surfacewithdiff <- function(t, y, p)
{
const=p["const"]
kay =p["kay"]
psii=p["psii"]
m1=p["m1"]
m2=p["m2"]
M=p["M"]
N=p["N"]
T=p["T"]
bexp<-as.brob((const*(psii-m1*y[1]-m2*M/N))/T)
yd1<-as.numeric((kay*exp(bexp))/(kay*t*exp(bexp)+1)-
(kay^2*t*exp(2*bexp))/(kay*t*exp(bexp)+1)^2)
list(c(yd1))
}
Now I guess this could be done with gmp.
Now I use this stuff in the function that odesolve's lsoda refers to,
and I have found that my approach using pure R code is not fast enough,
so I need to convert my function to C code. This is all on a windows
system.
Is it possible to access gmp or Brobdingnag dll's from the C code?
Or do I need to install and compile the gmp library itself?
I see that the gmp library for R contains the dll.
How do I access this from the C-code?
I see that according to the manual on extending R,
there are a heap of header file available for R functionality, but since
gmp is a contrib package, I guess it is not amongst them.
Kind regards,
Matt Redding
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